The present invention relates to an input device for positioning a cursor on a computer screen by movement of a ball relative to a substrate, and that these rotary movements of the ball are transformed into electronic signals.
The generally known input devices, such as computer mice, for the operation of a computer have certain drawbacks. The computer mouse requires some space available within the range of the computer user. Another requirement for the substrate of the mouse is that it must be a firm and plane as well as essentially horizontal substrate of a certain extent to enable the user to orient the screen projection of the mouse relative to the entire extent of the computer screen. It may sometimes be difficult or even impossible to place the computer such that the space required for the operation of the mouse is always available. Moreover, the known computer mouse solutions frequently give rise to pain in fingers and wrists after extended use.
Several attempts have been made to overcome these drawbacks, inter alia with several proposals for constructing the computer mouse as a ball-point pen. Such a xe2x80x9ccomputer penxe2x80x9d will be extremely convenient, easy and more precise to operate, it being possible to utilize the fact that the fine motor function of the fingers is considerably better developed than that of the arms. Further, no strict requirements are made with respect to the substrate on which the mouse is used.
A computer mouse constructed as a ball-point pen will also be able to expand the general use of computers.
Thus, it is conceivable that the future use of computers will inter alia comprise xe2x80x9chand-writtenxe2x80x9d letters or memos in electronic form. It will hereby be possible to impart a personal touch to the user of the computer, and to reduce the use of the keyboard completely or partly.
However, it has been found that the traditional embodiment of the arrangement for recording and transforming the movements of the ball into electrical signals requires a good deal of space particularly around the ball, which sets a limit to how small dimensions a pen-shaped computer mouse may be given. It is common to the know structures of xe2x80x9ccomputer pensxe2x80x9d that the external dimensions of the pen itself and of the ball are larger, and the computer pen hereby becomes more unhandy than ordinary ball-point pens.
The German Auslegeschrift No. DE 39 00 622 A1 describes a pen-shaped computer mouse, in which the recording of the movements of the ball is performed in that two rollers are in constant contact with the ball. The rollers rotate as a consequence of the rotation of the ball. A sensor unit is provided in connection with each of the rollers and records the rotation of the roller. The two rollers are arranged such that the movements of the ball in two directions relative to an x-axis and a y-axis may be recorded. This solution, which requires much space, resembles the normal rotation recording of the ball in an ordinary xe2x80x9cbox-shapedxe2x80x9d computer mouse, but with the difference that space is just available behind the ball in the ball-point pen structure. Thus, the tubular computer mouse according to DE-39 00 622 A1 cannot be manufactured with a very small cross-sectional diameter, as the tube, directly behind the ball, must be able to accommodate the entire space-requiring recording arrangement.
Another embodiment of a pen-shaped structure of a computer mouse is moreover known from U.S. Pat. No. 5,434,594. Here, the recording arrangement and the ball suspension are made in the same manner as in an ordinary xe2x80x9cbox-shapedxe2x80x9d mouse. The result is a computer mouse of such a structure that only to a limited extent can it be said to provide the expected advantages which are desired in connection with a pen-shaped computer mouse.
EP-A-0 413 606 describes a combined ball-point pen and computer mouse. It operates in that a flow meter is arranged directly above the ball, said flow meter measure the direction in which the ink moves as a consequence of the movement of the ball. This solution does not appear to be very reliable and only works as long as ink is present in the pen.
From U.S. Pat. No. 5,288,993 a track-ball device is known in which the ball is provided with randomly distributed speckles in contrasting colors, and light-sensitive sensor means, so that the movement of the ball can be detected. This detection concept takes up a considerable amount of space underneath and beside the ball and is for this reason alone not suitable for use in a pen-type solution. Furthermore, this device requires a ball of a diameter of at least 5 mm.
From WO94/22071 another optical solution is known. This device comprises photo-coupler means that can detect the movement of the ball of a golf ball type that is provided with concave reflectors (dimples). This device also takes up a considerable amount of space around the ball and requires a relatively large diameter that makes the solution unsuitable for a proper pen-type solution.
A similar solution is also shown from Xerox Disclosure Journal, Vol. 10, no. 3 pages 123-125, where a ball-point pen having a ball with dots in a contrast colour is described. The angular rotation of this ball is detected by use of LEDs or incandescent lamps. The xe2x80x98golf ballxe2x80x99 type solution is also mentioned in this disclosure.
Accordingly, the object of the invention is to provide an input device for a computer with a recording arrangement which requires considerably less space than the known solutions, thereby making it possible to construct a pen-shaped computer mouse in dimensions corresponding to a ball-point pen or similar writing utensil.
The invention comprises an input device of the introductory mentioned kind, wherein, said optical detection means comprising at leas. one source of substantially coherent electromagnetic radiation, at least one lens and one or more detectors.
This provides a recording arrangement for an input device which just contains few spacious components, and thus is advantageous in terms of space, as he optical detection means may be arranged at the rear side of the ball and only take up little room. This makes this principle suitable for the design of a computer pen, as it may be manufactured with a relatively small cross-sectional diameter since the detection means can be built with an elongated shape.
In a first preferred embodiment of the invention the optical detection means is adapted to detect the movement of the speckle pattern generated by the electromagnetic radiation scattered from the granular structure of the surface of the ball.
This is a particular simple way to carry out the detection, as the detection means according to this embodiment of the invention does not set out any special requirements to the surface of the ball.
The speckles arise when coherent light is scattered off the surface and made to interfere, constructively or destructively, as it propagates in free space. At a distance from the illuminated surface a strong intensity modulation is observed, which is usually named a xe2x80x9cspeckle patternxe2x80x9d. The coherent light is provided by a laser preferably of a VCSEL-type (VCSEL: Vertical Cavity Surface Emitting Laser), which is advantageous in that it has a very low electrical power consumption and a lower beam divergence.
The ball of a computer input device according to this first embodiment of the invention can be designed with a relatively very small diameter, as no special surface structure is required. A method of determining angular rotation of a cylindrical object by illuminating a spot of the object surface with coherent light is in general known from EP-B1-0 671 007.
In the first preferred embodiment the optical detection means comprises a first and a second sets of detectors and a common laser source, and each set of detectors are adapted to detect the angular rotation in a first and a second direction. In addition, comprises each set of detectors comprises two detectors that are arranged in such a way that a speckle pattern arising from the surface of the ball successively is detected by a first detector and then by a second detector by an angular rotation of the ball. Also, the transit time between the detected speckles can be determined by electronic means. Hereby a reliable measurement of the angular rotation of the ball in two directions can be carried out. Alternatively, the detectors could be arranged as a quad detector or similar detector arrays.
In an alternative embodiment, the surface of the ball is formed with optically detectable markings for the optical detection of movement. The reflection of the electromagnetic radiation or laser beam(s) from the surface is detected by the detectors and/or the CCD cameras, following which these signals are converted in an electronic signal processing unit into an electronic signal giving the direction in which the ball rotates. Reading of the markings is also performed in an optical system, which basically resembles the known code call systems from the compact disc technology and other forms of optical measuring devices.
The detectors according to this embodiment could also be arranged as quad detectors or as an array of detectors.
The optically detectable markings may advantageously be embedded in an information layer, either direct on the surface of the ball or on two shafts which are oriented preferably perpendicularly to each other, and to which the rotations of the ball are transferred, said marking layer being provided on these shafts. To protect the information layer, a preferably transparent protection layer may finally be applied to the information layer, as is known e.g. from compact discs.
In a preferred embodiment of the invention, the device is constructed as a computer pen comprising a tubular housing in which the ball is rotatably arranged at one end. Further, at the opposite end the computer pen may be connected to a computer either in the form of a cable connection or a wireless connection. In this embodiment, the pen will be provided with a transmitter and a power supply, such as a normal rechargeable battery. Keys may be arranged on the side of the substantively tubular housing to generate additional control signals for the connected computer. These keys as well as the substantively tubular housing are shaped and arranged in an ergonomically correct configuration.
In an embodiment, it is moreover conceivable to split the laser beam from the laser into two or more beams. As a supplement to the detectors or in substitution for one or more of the detectors, the detection means may moreover comprise one or more CCD cameras.
The electronic signal processing unit may be an integrated part of the pen, alternatively the optical signals just processed partly in the pen, following which the final signal processing is performed by an electronic signal processing unit which is incorporated in the transmission receiver in or attached to the computer.
The optically detectable markings may advantageously be embedded in an information layer, either directly on the surface of the ball or on two shafts which are oriented preferably perpendicularly to each other, and to which the rotations of the ball are transferred, said marking layer could be provided on these shafts. To protect the information layer, a preferably transparent protection layer may finally be applied to the information layer, as is known e.g. from compact discs.
The input device could further comprise a battery and associated battery capacity measuring means that can generate signals displaying the remaining capacity and transmit these signals to the computer. This means, that the user will have the possibility to monitor the status of the input device during use.